Due to the ever-increasing demand for information, plenty of portable electronic products, such as notebook computers, panel computers, and e-book readers, were developed. In addition to their functionality, commercially available electronic products are expected, by electronic product consumers, to be lightweight, compact, and portable. To this end, electronic product manufacturers attach great importance to the flatness of a circuit board inside an electronic product they manufacture. The manufacturing process of a circuit board for use with an electronic product entails welding plenty of electronic components. Thus, during the manufacturing process, the circuit board is often heated up or cooled down by solder, and in consequence the circuit board is deformed, more or less. Sometimes, a circuit board bends greatly or ends up with dislocation of holes/apertures when bent to thereby prevent the circuit board from being installed inside a casing of an electronic product and reduce the yield of the production of the electronic product. As a result, it is necessary to examine the curvature of a circuit board before the circuit board is installed inside the casing of an electronic product, otherwise whatever subsequent operations performed during the manufacturing process will be destined to fail.
Referring to FIG. 1, there is shown a schematic view of examining the curvature of a circuit board 1 according to the prior art. As shown in the drawing, to examine the circuit board 1, an examination worker puts the circuit board 1 on a platform 2 flatly, lifts a plug gauge 3 (0.4 mm thick approximately) manually in a manner that the plug gauge 3 faces the platform 2 closely, and eventually moves the plug gauge 3 along the margin of the platform 2 until the plug gauge 3 is positioned at a corner 11 of the circuit board 1. Possibility of moving the plug gauge 3 from the corner 11 to between the circuit board 1 and the platform 2 indicates that the curvature of the circuit board 1 exceeds the allowable tolerance and thus is unfit for a subsequent assembly operation. Impossibility of moving the plug gauge 3 from the corner 11 to between the circuit board 1 and the platform 2 indicates that the curvature of the circuit board 1, at the corner 11, falls within the allowable tolerance. Afterward, other corners 12, 13, 14 are manually examined by the examination worker with the plug gauge 3. A failure to move the corners 11, 12, 13, 14 to between the circuit board 1 and the platform 2 with the plug gauge 3 indicates that the curvature of the circuit board 1 in its entirety falls within the allowable tolerance and thus does not prevent any subsequent assembly operation from being carried out on the circuit board 1. However, it is time-consuming and laborious to lift the plug gauge 3 manually in order to examine the corners 11, 12, 13, 14 of the circuit board 1 solely for the purpose of examining the curvature of the circuit board 1. Also, examination is unlikely to be accurate when it is carried out by lifting the plug gauge 3 manually and examining the corners 11, 12, 13, 14 of the circuit board 1, because, in so doing, the examination worker does not always make sure that the plug gauge 3 is facing the platform 2 flatly and closely.
Referring to FIG. 2, there is shown another schematic view of examining the curvature of the circuit board 1 according to the prior art. As shown in the drawing, a conventional process of examining the curvature of the circuit board 1 is inconvenient when a protrusion 17 of a relatively large size is disposed on the circuit board 1 by soldering. Examination of the curvature of the circuit board 1 is inaccurate, because the circuit board 1 lying on the platform 2 is tilted by the protrusion 17. A remedial approach, though an inconvenient one, to improving the accuracy of examination entails putting the circuit board 1 on the platform 2 at a position thereof such that the protrusion 17 soldered to the circuit board 1 is outside of the platform 2 so as to make sure that the circuit board 1 lies flatly on the platform 2. Afterward, the corner 11 of the circuit board 1 is examined with the plug gauge 3. The inconveniency thus incurred repeats whenever the circuit board 1 has to be carefully positioned on the platform 2 in order for the protrusion 17 to lie outside the platform 2 before the commencement of the examination of the corners 12, 13, 14 of the circuit board 1.
Accordingly, it is imperative to provide a jig for examining the curvature of a circuit board quickly and accurately.